1. Field of the Invention
The present invention relates to an input device, and in particular to an input device having a contact sensing surface, wherein the contact sensing surface is provided with a key region with changeable functions based on a sliding trajectory detected within the key region.
2. Description of Prior Art
There are many kinds of input devices used for electronic products, such as mechanical keys at an earlier stage, a keyboard, a mouse, a handwriting tablet, and a touch pad for a modern portable electronic product. The input device has evolved from a single-function mode into an integrated multiple-function mode.
In addition to directly combine a keyboard, a touch pad and a handwriting tablet into one input module, an integrative touch pad with functions of track pad and key pad is developed. The contact sensing surface of a touch pad can detect the contact action of an object and output the position of the object on the contact sensing surface. Therefore, a touch pad can be used for an integrative input device by dividing its contact sensing surface into several regions: one for the key pad, one for the track pad, and even more for the handwriting pad.
Using the several regions on the contact sensing surface for integrating track pad and key pad can save a space for arranging mechanical keys, connecting lines and control ICs. Thus, the touch pad is widely used in various kinds of compact portable electronic devices. Even, the contact sensing surface is provided on a casing of a traditional mouse for integrating the functions of a left key, a right key, and a scrolling wheel.
When more keys are used, a larger key pad region for arranging these keys is needed. As a result, the dimension of the contact sensing surface is getting larger, which not only violates the requirements for compact design but also reduces the convenience in use due to the complicated arrangement of keys.
Thus, a common solution is used via a mode switch. For example, the whole contact sensing surface is used as a track pad for cursor operation mode and changed to a key pad when an external button (switch) is pressed. Through a switch between different modes, even a small-size contact sensing surface can provide more than one input mode.
However, switching modes takes time for launching a different operation mode and it may interrupt the input operation. When the user has to alternately switch between modes, it makes a lot of very inconvenience and takes a lot of waiting time for every mode switch. For example, scrolling up/down, paging up/down, rotating images, zooming in/out a window, playing audio/video signals, forwarding, and reversing are frequently used in Window System.
Therefore, if a key region of the contact sensing surface has more than one corresponding functions which can be switched without a prior switching action, the diversity, highly-integrated property, and convenience of an input device can be dramatically improved.